Without a full sleep you can not live a normal life. First, a person who sleeps less than seven hours, feels worse, as there is a disruption of the heart, stomach, intestine, and the process of metabolism. Second, there is a set of extra pounds, because if a person spends all night on his feet, he should at this time something to eat. But if he slept, then fill his stomach would not have to, because during sleep is a synthesis of hormones that suppress hunger. Well, and thirdly, in the absence of mental abilities of normal sleep and worse -it is the weakening of memory, which prevents good think. These are the conclusions were made after a study of sleep physiology researchers from the University Hospital of Regensburg in Bavaria. So, for effective work we need at least seven hours of sleep.